1. Field of the Invention
The present invention relates to a half-duplex radio communication method, a program and a system for establishing half-duplex radio communication between radio communication terminals.
2. Description of the Prior Art
A conventional half-duplex radio communication system is comprised of carrier systems (communication control systems) managed by carriers, connected with each other. Each carrier system is provided with a CUG (Closed User Group) server.
For the establishment of half-duplex radio communication, a user needs a previous member entry from a PC (Personal Computer) or the like, and a CUG of radio communication terminals belonging to a carrier system is registered with the CUG server. After the registration of the CUG, half-duplex radio communication becomes possible within the CUG.
As the prior art of the carrier system, the Japanese Patent Application laid open No. 2000-244508 discloses a system in which an operator inputs information to a user interface part, and a node information database maintains the information on connected nodes with a CUG number as a key. Then, the entries in a routing table of all nodes corresponding to the CUG and the nodes to which the additional members are connected are set based on the CUG number, member information and node information.
However, in the conventional half-duplex radio communication system described above, the user interfaces and the operating procedures to perform the functions differ depending on the respective carrier systems. Further, an access to a CUG between different carrier systems is not generally allowed from a point of view of privacy protection, and therefore, it is not possible to establish radio communication between different carrier systems.
As a result, there has been a problem in that even if, for example, the police station or the fire station tries to perform emergency multicasting, it is not possible to send emergency multicasts to the systems of different carriers.
Besides, although the system disclosed in the patent application described above spares an operator the trouble of correcting and setting routing information, the operator needs to input, from the user interface part, information on members to be added to the CUG and the like. Further, the system still has the problem described above.